Swash plate type compressor

ABSTRACT

The object of the present invention is to offer a swash plate type compressor, wherein a swash plate is smoothly rotated relative to a drive shaft, whereby noise and vibration in the direction perpendicular to the drive shaft are reduced, and wherein a roller bearing with small frictional resistance is used, whereby mechanical loss is reduced.  
     The swash plate type compressor comprises, a housing having a crank chamber and a plurality of cylinder bores therein, pistons, the drive shaft and the swash plate supported by the supporting member and converting the rotation of the drive shaft to the reciprocating movement of the pistons. A supporting member, which has a supporting surface crossing with respect to an axis of the drive shaft at a certain angle and a supporting shaft portion formed perpendicular to the supporting surface, is integrally and rotatably mounted around the drive shaft. The swash plate is rotatably supported relative to the supporting member through a thrust bearing on the supporting surface, and through the roller bearing as a radial bearing around the supporting shaft portion.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a fixed capacity type swash plate compressor.

[0002] Conventionally as a fixed capacity type swash plate compressor, a swash plate rotated integrally with a drive shaft is generally used. A swash plate type compressor, which has a supporting surface rotated integrally with the drive shaft and a swash plate supported slidably on the supporting surface, is disclosed in Japanese Examined Utility Model Publication No. 63-20864.

[0003] In the swash plate type compressor disclosed in the publication, the swash plate is supported through a ball joint mechanism composed of a ball socket and a ball retainer around the drive shaft. That is, a load in the radial direction of the swash plate is supported through a sliding bearing surface of the ball joint. A load in the thrust direction of the swash plate is supported through a roller bearing arranged between the swash plate and the supporting surface.

[0004] In Japanese Unexamined Patent publication No. 10-184539, a load in the radial direction is supported through a sliding bearing arranged between a swash plate and a supporting shaft portion, and a load in the thrust direction is supported through a roller bearing arranged between the swash plate and a supporting surface.

[0005] In recent years, a carbon dioxide gas is considered to be a substitution of a freon gas as a refrigerant gas of the compressor. When the refrigerant gas such as a carbon dioxide gas, which needs a high compression ratio, is used, the compressor is run in high pressure and with a small volume. Therefore, its drive shaft has to be rotated at a high speed, in order to raise the cooling capacity.

[0006] However, in Japanese Examined Utility Model Publication No. 63-20864 and Japanese Unexamined Patent Publication No. 10-184539, the sliding bearing is used between the swash plate and the supporting surface, so that the swash plate is not smoothly rotated relative to the drive shaft and the mechanical loss is increased. In particular, when the drive shaft is rotated at a high speed, or the refrigerant gas is compressed at a multistage, the above problem is remarkable.

SUMMARY OF THE INVENTION

[0007] The present invention is performed, considering the above problems, and the object of it is to offer a swash plate type compressor, wherein a swash plate is smoothly rotated relatively to a drive shaft, whereby noise and vibration in the direction perpendicular to the drive shaft are reduced, and wherein a roller bearing with small frictional resistance is used, whereby mechanical loss is reduced.

[0008] To solve the above problems, the present invention has following features. The swash plate type compressor comprises a housing having a crank chamber and a plurality of cylinder bores therein, the drive shaft inserted in the crank chamber so as to be rotated, pistons accommodated in the cylinder bores so as to be reciprocated, a supporting member mounted around the drive shaft to be rotated integrally with the drive shaft, the supporting member having a supporting surface and a supporting shaft portion, the swash plate supported by the supporting member and converting the rotation of the drive shaft to the reciprocating movement of the pistons. The supporting surface crosses with respect to an axis of the drive shaft at a certain angle and the supporting shaft portion is formed perpendicular to the supporting surface to be mounted around the drive shaft, and the swash plate is rotatably supported relative to the supporting member through a thrust bearing between the supporting surface and the swash plate and through the roller bearing between the supporting shaft portion and the swash plate. According to the present invention, the noise and the vibration in the direction perpendicular to the drive shaft are reduced, since the swash plate is smoothly rotated relative to the drive shaft. Moreover, the mechanical loss can be reduced, since the roller bearing with small frictional resistance is used.

[0009] Furthermore, the present invention has following features. The drive shaft is driven by an electric motor. According to the present invention, since the rotational speed of the drive shaft is changed by the electric motor, even if the stroke of the piston is fixed, the cooling capacity can be adjusted.

[0010] Furthermore, the present invention has following features. The swash plate type compressor is a multistage type having a compression chamber in lower pressure, where the refrigerant gas from the external refrigerant circuit is compressed, and a compression chamber in higher pressure, where the refrigerant gas in intermediate pressure, at least once compressed, is drawn and compressed. According to the present invention, the refrigerant gas, which needs a high compression ratio, can also be used in the compressor, without increasing the size of the compressor.

[0011] Furthermore, the present invention has following features. The piston is operably connected to the swash plate through a pair of semispherical shoes sandwiching the swash plate. According to the present invention, the shoes and the pistons are easily assembled.

[0012] Furthermore, the present invention has following features. Carbon dioxide gas is used as the refrigerant gas. According to the present invention, the compressor can be compact.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The invention together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which:

[0014]FIG. 1 is a cross-sectional view illustrating a swash plate type compressor according to a first embodiment of the present invention;

[0015]FIG. 2(a) is a partial cross-sectional view illustrating a swash plate type compressor according to the first embodiment of the present invention;

[0016]FIG. 2(b) is a view similar to FIG. 2(a), except that the phase of the drive shaft is different from that in FIG. 2(a) by an angle of 180 degrees;

[0017]FIG. 3 is a cross-sectional view as seen from line I-I in FIG. 4 illustrating a swash plate type compressor according to a second embodiment of the present invention; and

[0018]FIG. 4 is a cross-sectional view as seen from line II-II in FIG. 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Embodiment 1

[0020] A first embodiment applied to an electric type swash plate compressor according to the present invention will now be described in FIGS. 1, 2(a) and 2(b).

[0021] As shown in FIG. 1, a swash plate type compressor has a motor housing 11, a front housing 12, a cylinder block 13 and a rear housing 14. Each of the housings 11, 12, 14, and the cylinder block 13 are secured each other with through bolts which are not illustrated, and constitute an outer casing of the compressor substantially in a cylindrical shape. A motor chamber 15 is defined in a region surrounded by the motor housing 11 and the front housing 12. A crank chamber 16 is defined in a region surrounded by the front housing 12 and the cylinder block 13.

[0022] A drive shaft 17, which is inserted into the motor chamber 15 and the crank chamber 16, is rotatably supported through front and rear radial bearings 18A and 18B, between the motor housing 11 and the cylinder block 13. The drive shaft 17 is loosely inserted into a central bore 12B of a front wall 12A formed in the front housing 12.

[0023] In the motor chamber 15, an electric motor 21 composed of a stator 19 and a rotor 20, is accommodated. The rotor 20 is integrally and rotatably fixed on the drive shaft 17.

[0024] In the crank chamber 16, a supporting member 22 having a supporting surface 22A and a supporting shaft portion 22B is integrally and rotatably fixed on the drive shaft 17 through a thrust bearing 23 on a front wall 12A of the front housing 12. The supporting surface 22A and an axis of the drive shaft 17 cross at a certain angle, and the supporting shaft portion 22B is formed perpendicular to the supporting surface 22A.

[0025] The swash plate 26 in a ring shape is arranged on the supporting member 22 through a thrust bearing 24 on the supporting surface 22A and through a roller bearing 25 as a radial bearing around the supporting shaft portion 22B respectively. The swash plate 26 is penetrated and slidably supported by the supporting shaft portion 22B in a state the swash plate 26 is prevented from slipping off from the supporting shaft portion 22B. The drive shaft 17 and the supporting member 22 are positioned in the thrust direction (in the direction of axis of the drive shaft) by the thrust bearing 23 and a washer 28, which is urged forward by a spring 27 placed in a recess formed in the center of the cylinder block 13.

[0026] In the cylinder block 13, a plurality (two in this embodiment) of cylinder bores 13A having an equal diameter are formed. In the cylinder bore 13A, a single-headed type of piston 29 is accommodated so as to reciprocate back and forth slidably, and a compression chamber 30 which changes its volume in accordance with reciprocating movement of the piston 29 is defined therein. In the front part of the piston 29, a concave portion 29A is formed, and a pair of substantially semispherical shoes 31 are arranged therein. Circumferential portion of the swash plate 26 is slidably sandwiched by a pair of shoes 31, so the piston 29 is operably connected to the swash plate 26. The supporting member 22 rotates synchronously with the drive shaft 17 which is rotated by the electric motor 21, and the swash plate 26 which contacts the supporting surface 22A is oscillated. Therefore, the rotational movement of the supporting member 22 is converted into liner reciprocating movement of the piston 29 with the stroke in accordance with the inclination angle of the supporting surface 22A with respect to the axis of the drive shaft 17.

[0027] A valve plate assembly 32 is sandwiched between the cylinder block 13 and the rear housing 14. A suction chamber 33 is defined between the valve plate assembly 32 and the rear housing 14. The refrigerant gas drawn from the external refrigerant circuit (not illustrated) is introduced into the suction chamber 33 through an intake port 33A formed in the circumferential wall of the rear housing 14. A discharge chamber 34 is defined between the valve plate assembly 32 and the rear housing 14. The discharge chamber 34 communicates with the external refrigerant circuit through an outlet port 34A formed in the rear wall of the rear housing 14.

[0028] The valve plate assembly 32 comprises a suction valve disk 35, a valve plate 36, discharge valves 37, retainers 38 and a pin 39.

[0029] In the valve plate 36, ports 36A and 36B are formed. The port 36A communicates the suction chamber 33 with the cylinder bore 13A, and the port 36B communicates the cylinder bore 13A with the discharge chamber 34.

[0030] On the suction valve disk 35, suction valves 35A are formed in position corresponding to the ports 36A. In the discharge chamber 34, the discharge valves 37 and the retainers 38 are attached to the suction valve disk 35 and the valve plate 36 by the pin 39.

[0031] Next, the operation of the above compressor is described.

[0032] The supporting member 22 and the swash plate 26 are illustrated in FIG. 2(a) and 2(b) where the phases of the drive shaft 17 are different from each other by an angle of 180 degrees. When the drive shaft 17 is rotated by the electric motor 21, the supporting member 22 integrally rotates with the drive shaft 17. Conventionally, the swash plate 26 is supported through a sliding bearing around the supporting shaft portion 22B. Therefore, the conventional swash plate 26 tends to be rotated integrally with the supporting member 22 by the frictional resistance therebetween when the drive shaft 17 changes its phase between FIG. 2(a) and FIG. 2(b). In the embodiment of the present invention, however, the swash plate 26 tends to be rotated relative to the supporting member 22, since the swash plate 26 is supported through the roller bearing 25 around the supporting shaft portion 22B. Therefore, the swash plate 26 is supported on the supporting member 22, or, on the drive shaft 17 via the supporting member 22, through the roller bearing 25 between the supporting shaft portion 22B and the swash plate 26, and through the thrust bearing 24 between the supporting surface 22A and the swash plate 26, so that the drive shaft 17 smoothly changes its phase between FIG. 2(a) and FIG. 2(b).

[0033] The swash plate 26 is oscillated by the rotational movement of the supporting member 22, whereby the piston 29 is reciprocated through a pair of shoes 31. In the compression chamber 30, the processes of drawing, compressing and discharging the refrigerant gas are repeated in turn.

[0034] The refrigerant gas drawn from the intake port 33A to the suction chamber 33 is drawn into the compression chamber 30 through the port 36A, and the refrigerant gas is compressed by the movement of the piston 29. Then the refrigerant gas is discharged into the discharge chamber 34 through the port 36B. The refrigerant gas is sent out to the external refrigerant circuit through the outlet port 34A.

[0035] In this embodiment, the following effects can be obtained.

[0036] (1) The swash plate 26 is slidably supported on the supporting member 22 through the radial bearing 25 and the thrust bearing 24. Therefore, the frictional resistance caused between the supporting member 22 and the swash plate 26 is small, and the swash plate 26 tends to be rotated relative to the rotation of the supporting member 22. Accordingly, the rotational speed of the swash plate 26 is reduced, and the vibration in the direction perpendicular to the drive shaft 17 is reduced.

[0037] (2) Since the rotational speed of the swash plate 26 is reduced, the frictional force caused between the shoes 31 and the swash plate 26 is reduced, and the vibration and the noise are reduced.

[0038] (3) Since the vibration and the frictional resistance of each portions are reduced, the mechanical loss is reduced, and the noise is also reduced.

[0039] (4) Since the rotational speed of the swash plate 26 is reduced, the sliding portions such as between the shoes 31 and the swash plate 26, and between the swash plate 26 and the supporting member 22, are smoothly lubricated.

[0040] (5) Since the compressor is driven by the electric motor 21, the rotational speed of the drive shaft 17 is changed in accordance with the rotational speed of the electric motor 21. Therefore, the discharge volume of the refrigerant gas per the time can be controlled freely.

[0041] Embodiment 2

[0042] The second embodiment applied to a multistage type compressor according to the present invention will be now described in FIGS. 3 and 4. In this embodiment, the same reference numerals as the first embodiment are given to the components which are common to the first embodiment, and the overlapped description is omitted. Accordingly, the different points from the first embodiment are mainly explained.

[0043] A first cylinder bore 13B and a second cylinder bore 13C, which has a smaller diameter than the first cylinder bore 13B, are formed around the drive shaft 17 in the cylinder block 13 so that the difference between the cylinder bores 13B and 13C in phase is an angle of 90 degrees by turns. A single-headed type of first piston 40A and second piston 40B are respectively accommodated so as to reciprocate back and forth slidably in each cylinder bores 13B and 13C. A compression chamber in lower pressure 41A and a compression chamber in higher pressure 41B, which change each volume in accordance with reciprocating movement of each pistons 40A and 40B, are respectively defined in each cylinder bores 13B and 13C. In the front part of each pistons 40A and 40B, concave portions 40C and 40D are respectively formed. Since circumferential portion of the swash plate 26 is slidably sandwiched by a pair of shoes 31 arranged in the concave portions 40C and 40D, each pistons 40A and 40B are operably connected to the swash plate 26.

[0044] The valve plate assembly 42 is sandwiched between the cylinder block 13 and the rear housing 14. As shown in FIGS. 3 and 4, the suction chamber 33, the intermediate pressure chamber 43 communicating with each cylinder bores 13B and 13C, and the discharge chamber 34 are defined between the valve plate assembly 42 and the rear housing 14. Two suction chambers 33 around the intermediate pressure chamber 43 are communicated through a communication passage 33B.

[0045] The valve plate assembly 42 comprises a suction valve disk 44, a valve plate 45, first and second discharge valves 46A and 46B, first and second retainers 47A and 47B, and pins 48A and 48B.

[0046] Ports 45A, 45B, 45C and 45D are formed in the valve plate 45. The port 45A communicates the suction chamber 33 with the first cylinder bore 13B. The port 45B communicates the first cylinder bore 13B with the intermediate pressure chamber 43. The port 45C communicates the second cylinder bore 13C with the intermediate pressure chamber 43. The port 45D communicates the second cylinder bore 13C with the discharge chamber 34.

[0047] On the suction valve disk 44, suction valves 44A are formed in the position corresponding to the ports 45A and 45C. In the intermediate pressure chamber 43, the first discharge valve 46A and the first retainer 47A are attached to the suction valve disk 44 and the valve plate 45 by the pin 48A. In the discharge chamber 34, the second discharge valve 46B and the second retainer 47B are attached to the suction valve disk 44 and the valve plate 45 by the pin 48B.

[0048] In this embodiment, carbon dioxide gas is used as the refrigerant gas.

[0049] Next, the operation of the above compressor is described.

[0050] When the drive shaft 17 is rotated by the electric motor 21, the supporting member 22 integrally rotates with the drive shaft 17. The swash plate 26 oscillates in accordance with the rotation of the supporting member 22, and each pistons 40A and 40B reciprocate respectively through shoes 31. In each compression chambers 41A and 41B, the processes of drawing, compressing and discharging the refrigerant gas are repeated in turn.

[0051] The refrigerant gas drawn from the intake port 33A to the suction chamber 33 is drawn into the compression chamber 41A through the port 45A, and the refrigerant gas is compressed by the movement of the first piston 40A. Then the refrigerant gas is discharged into the intermediate pressure chamber 43 through the port 45B. The refrigerant gas in the intermediate pressure chamber 43 is drawn into the compression chamber 41B through the port 45C, and is compressed by the second piston 40B. Then the compressed refrigerant gas is discharged into the discharge chamber 34 through the port 45D. The refrigerant gas is sent out to the external refrigerant circuit through the outlet port (not illustrated).

[0052] In this embodiment same as in the first embodiment, the swash plate 26 is supported on the supporting member 22 through the roller bearing 25 between the supporting shaft portion 22B and the swash plate 26, and through the thrust bearing 24 between the supporting surface 22A and the swash plate 26. As described above, the refrigerant gas is compressed in the process of two stages.

[0053] According to this embodiment, in addition to the effects of the first embodiment from (1) to (5), the following effects can be obtained.

[0054] (6) Since the refrigerant gas is compressed in the process of two stages, even the refrigerant gas such as carbon dioxide gas, which needs a high compression ratio, can be used in the compressor, without increasing the size of the compressor.

[0055] (7) A large number of the pistons are applied in the multistage compressor, and the mechanical loss tends to increase. However, the swash plate 26 is supported through the roller radial bearing 25 around the supporting shaft portion 22B, and the frictional loss can be reduced.

[0056] (8) The vibration and noise of each portions are reduced more than the first embodiment.

[0057] These embodiments are not limited to be above mentioned structures, but the following embodiments also can be performed.

[0058] The electric motor 21, which is separated from the drive shaft 17, can be arranged inside the compressor, and the drive shaft 17 can be connected to the output shaft of the electric motor 21.

[0059] The electric motor 21 can be arranged outside the compressor.

[0060] The power of engine can be applied as a driving source instead of the electric motor 21.

[0061] The supporting member 22 and the drive shaft 17 can be unified.

[0062] In the second embodiment, the suction chamber 33, the intermediate pressure chamber 43 and the discharge chamber 34 are formed in order from the outer side of the compressor toward the center. However, in the present invention the form and the arrangement of the suction chamber 33, the intermediate pressure chamber 43 and the discharge chamber 34 are not limited to be above mentioned structures.

[0063] While the cylinder bores 13A, 13B and 13C are respectively in sets of two in the first embodiment and the second embodiment, more than two cylinder bores can be used. In the present invention, the number of the set of cylinder bores is not limited.

[0064] As described above in detail, according to the present invention, since the swash plate is smoothly rotated relative to the drive shaft, the noise and the vibration in the direction perpendicular to the drive shaft are reduced. Besides, since the roller bearing with small frictional resistance is used, the mechanical loss can be reduced.

[0065] Furthermore, since the rotational speed of the drive shaft is easily changed by the electric motor, even if the stroke of the piston is fixed, the cooling capacity can be adjusted.

[0066] Furthermore, the refrigerant gas, which needs a high compression ratio, can also be used in the compressor, without increasing the size of the compressor.

[0067] Furthermore, the shoes and the pistons are easily assembled.

[0068] Furthermore, the compressor can be compact.

[0069] Therefore the present examples and embodiments are to be considered as illustrative and not restrictive and the invention is not to be limited to the details given herein but may be modified within the scope of the appended claims. 

What is claimed is:
 1. A swash plate type compressor comprising: a housing having a crank chamber and a plurality of cylinder bores therein; a drive shaft inserted in said crank chamber so as to be rotated; pistons accommodated in said cylinder bores so as to be reciprocated; a supporting member mounted around said drive shaft to be rotated integrally with said drive shaft, said supporting member having a supporting surface and a supporting shaft portion; and a swash plate supported by said supporting member and converting the rotation of said drive shaft to the reciprocating movement of said pistons; wherein said supporting surface crosses with respect to an axis of said drive shaft at a certain angle, and said supporting shaft portion is formed perpendicular to said supporting surface to be mounted around said drive shaft, and wherein said swash plate is rotatably supported relative to said supporting member through a thrust bearing between said supporting surface and said swash plate and through a roller bearing between said supporting shaft portion and said swash plate.
 2. The swash plate type compressor according to claim 1 , wherein said drive shaft is driven by an electric motor.
 3. The swash plate type compressor according to claim 1 , wherein said swash plate compressor is a multistage type having a compression chamber in lower pressure, where a refrigerant gas drawn from an external refrigerant circuit is compressed, and a compression chamber in higher pressure, where the refrigerant gas in intermediate pressure, at least once compressed, is drawn and compressed.
 4. The swash plate type compressor according to claim 1 , wherein said piston is operably connected to said swash plate through a pair of semispherical shoes sandwiching said swash plate therebetween.
 5. The swash plate type compressor according to claim 3 , wherein carbon dioxide gas is used as the refrigerant gas. 